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[blake floyds]

Hello can you help

building an extension have my bricks up to damp course

can you tell me what i need to do for the floor I can not get in touch with my building inspector


dose it go like this

Hardcore

blinding

sand

200 mm insulation (this is what I been Told , I thought it was 100 mm )

100 mm concrete slab

screed floor[/u]

 

[^woody^]

Hardcore - minimum 100mm

blinding sand - 25mm

DPM

Insulation - 150mm polystyrene or 80mm Kingspan/Celotex

100 mm concrete slab

70mm screed (optional)

Don't forget 25mm thick insulation upstand around the edge of the slab where it butts up to an external wall

 

[GaryinAshby]

My BCO also told me to put in a polythene membrane (just standard stuff, not a DPM) between the Celotex & concrete slab.

 

[^woody^]

There is no need for that, did he say why?

 

[GaryinAshby]

No, just told me there had to be a barrier between the insulation & concrete, despite there being a full DPM under the insulation. As I had a lot of large polythene sheets lying around I didn't question it.

 

[noseall]

they insist upon this method in Staffs also.

 

[Shytalkz]

It's to stop screed/concrete getting between the sheets and causing cold bridging. It's not an extra dpm.

 

[^woody^]

Well surely its better to have no gaps between the sheets, then nothing falls through!

 

[Shytalkz]

Indeed. If you use the stuff with the membrane already on the top and taped joints, there isn't a problem. If it's just EPS or somesuch, then that's when the BCOs insist on it.

 

[^woody^]

"Yeah, of course I'll put it in " he thinks while waving the BCO goodbye

What a waste of time

 

[blake floyds]

can I put my insulation on top of the slab so i can put under floor heating on it

 

[Deluks]

In a word, no. Follow the advice given, and use insulation board for underfloor heating in addition to the celotex. Belt and braces, very warm floor, will save you dough. If you mean wet underfloor heating, then this goes into the floor screed anyway and won't need any other insulation.

 

[^woody^]

A wet system should be fitted on top of the insulation and then screeded